Our behaviour fall between highly rational to highly emotional/irrational. On 1-9 scale say 9 is for highly rational and 1 is for highly emotional. Geeta explains it beautifully. Every living being have combination of 3 qualities. रज, तम व सत. I will relate highly rational as rajoguni and highly emotional as tamoguni. If you balance between rational and emotional than you can be termed as satoguni.
Whether we will act as rajoguni, tamoguni or satoguni depends on 4 aspects. Self, other person, time and circumstances. The problem with humans is that in same circumstances they may act differently with different people or different time. That way we are unpredictable.
Self is guided by gene, upbringing, education, experiences and self interest. Our tuning with other person also plays big role. What phase of time we are going through can also change our behaviour and what circumstances we are going through also decides our actions and reactions.
So our behaviour or behaviour of other person depends on complexity of time, situation, person and self (emotions and intellect). It is easy to predict satoguni (balanced person) compared to rajoguni (rational) or tamoguni (emotional).